Testfixtures

--------------------

- Fix bug where new-style classes had their attributes checked with :func:`compare` even
when they were of different types.

--------------------

- Fix bugs in :func:`compare` when comparing objects which have both ``__slots__``
and a ``__dict__``.

-------------------

- Fix edge case where string interning made dictionary comparison output much less useful.

--------------------

- Better feedback where objects do not :func:`compare` equal but do have the same
representation.

-------------------

- Fix deprecation warning relating to ``getargspec``.

- Improve :doc:`mocking <mocking>` docs.

- Added ``strip_whitespace`` option to :class:`OutputCapture`.

- When ``separate`` is used with :class:`OutputCapture`, differences in ``stdout`` and ``stderr``
are now given in the same :class:`AssertionError`.

- :class:`ShouldRaise` no longer catches exceptions that are not of the required type.

- Fixed a problem that resulted in unhelpful :func:`compare` failures when
:func:`~unittest.mock.call` was involved and Python 3.6.7 was used.

Thanks to Łukasz Rogalski for the deprecation warning fix.

Thanks to Wim Glenn for the :class:`ShouldRaise` idea.

------------------

- Fix handling of the latest releases of the ``mock`` backport.